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[BlueGas]

I knew how to find the GA, but length of FA was confusing, in the answers, they say: In triangle AFB, sintheta = AF/15, but where's theta in triangle AFB?

 

[BlueGas]

Bump.

 

[rand_althor]

Angle BAD is 90 degrees. Angles BAF, BAD and GAD add up to 180 degrees as they are on a straight line. Using this, angle BAF is 90-θ. Using the angle sum of a triangle, angle FBA is θ.

 

[Flop21]

Is this right?

< AFB = theta + 90 + x = 180 (straight line sum) > = 90 - theta

So to find FA, we need to use cos to get > cos(90-theta) = x/15

Then that cos turns into sin, because of the 90-theta, so

Sin(theta) = x/15

15*Sin(theta) = x = FA

 

[BlueGas]

Is this right?

<AFB = theta + 90 + x = 180 (straight line sum) > = 90 - theta

So to find FA, we need to use cos to get > cos(90-theta) = x/15

Then that cos turns into sin, because of the 90-theta, so

Sin(theta) = x/15

15*Sin(theta) = x = FA

https://gyazo.com/3426f50d87716ee61b57e2f585a960be

Angle BAD is 90 degrees. Angles BAF, BAD and GAD add up to 180 degrees as they are on a straight line. Using this, angle BAF is 90-θ. Using the angle sum of a triangle, angle FBA is θ.

Now it makes sense, thanks everyone!